What is a Cyst? Synovial cysts, ganglia and cutaneous mucoid cysts are essentially the same thing. All three refer to a fluid filled mass under the skin. The fluid looks a lot like corn syrup or the white of an egg. Most are located under the skin, although occasionally they may be found in the tendon or the bone. The synovial or ganglionic cysts are connected to a nearby joint or tendon sheath by a small stalk (stem). They therefore may be more resistant to treatment. Mucoid cysts are not connected to a joint. If the cyst is located near the nail, it may cause the nail to grow funny.
How does it feel? Many mucous cysts are painless. Some people are worried about the way it looks; others worry that it may be a serious problem. The cysts are more likely to cause pain or discomfort when they are on the foot, because of pressure created by shoes on them. Occasionally, the cyst encloses or presses on a nerve, causing a shooting, electric type of pain.
Causes: The cysts may form on their own, or may branch out from a joint. Most doctors feel that these cysts form as a result of small injuries that occur repeatedly over a long period of time. Essentially, they can be thought of as bubbles made of a thin layer of specialized cells that produce the fluid.